feat: Backlinks (#979)

* feat: backlinks

* feat: add backlinkDocumentId to documents.list

* chore: refactor
fix: create and delete backlink handling

* fix: guard against self links

* feat: basic frontend
fix: race condition

* styling

* test: fix parse ids

* self review

* linting

* feat: Improved link styling

* fix: Increase clickable area at bottom of doc / between references

* perf: global styles are SLOW

app/scenes/Document/Document.js

@@ -22,6 +22,7 @@ import { emojiToUrl } from 'utils/emoji';
 import Header from './components/Header';
 import DocumentMove from './components/DocumentMove';
 import Branding from './components/Branding';
+import Backlinks from './components/Backlinks';
 import ErrorBoundary from 'components/ErrorBoundary';
 import LoadingPlaceholder from 'components/LoadingPlaceholder';
 import LoadingIndicator from 'components/LoadingIndicator';
@@ -415,6 +416,12 @@ class DocumentScene extends React.Component<Props> {
                 ui={this.props.ui}
                 schema={schema}
               />
+              {!this.isEditing && (
+                <Backlinks
+                  documents={this.props.documents}
+                  document={document}
+                />
+              )}
             </MaxWidth>
           </Container>
         </Container>